Color control of polyester-cobalt compounds and polyester-cobalt compositions

ABSTRACT

The present invention is to a composition made from a polyester produced by the acid or ester polyester process, a cobalt salt and a base, preferably an alkaline metal base. The composition can be made by blending a cobalt salt with a polyester which has been polymerized in the presence a alkaline metal ion derived from a basic alkaline metal compound, e.g. alkaline metal base or basic alkaline metal salt. The composition may optionally comprise an ionic compatibilizer, which may further be blended with a partially aromatic polyamide. This blend can be processed into a container having both active and passive oxygen barrier with an improved color and clarity than that achieved by cobalt alone. The use of the cobalt salt in combination with the base can also be used to improve the color of recycled polyester during processing.

PRIORITY AND CROSS REFERENCES

This specification claims priority from U.S. Patent Provisional PatentApplications 61/560,802 filed on 16 Nov. 2011, 61/710,652 filed on 5Oct. 2012 and 61/726,036 filed on 14 Nov. 2012, and InternationalApplication Number PCT/US2012/065351 filed on 15 Nov. 2012. Theteachings of which are incorporated by reference in their entirety withrespect to the compounds, compositions and the teachings both the esterand acid process of manufacturing the compounds and compositions.

BACKGROUND OF THE INVENTION

1) Field of the Invention

The invention relates to the incorporation of cobalt and a base into apolyester produced from the acid or ester process. The composition canbe used in compatibilized blends of polyamides in polyesters, a methodfor forming such compositions, and to containers made from suchcompositions. Specifically a composition made from thepolyester-cobalt-base has less yellowness than other compositions. Theblends can be used as passive gas barriers, or active oxygen scavengerswhen combined with a partially aromatic polyamide or other oxidizableorganic compound.

2) Prior Art

Plastic materials have been replacing glass and metal packagingmaterials due to their lighter weight, decreased breakage compared toglass, and potentially lower cost. One major deficiency with polyestersis its relatively high gas permeability. This restricts the shelf lifeof carbonated soft drinks and oxygen sensitive materials such as beerand fruit juices.

Multilayer bottles containing a low gas permeable polymer as an innerlayer, with polyesters as the other layers, have been commercialized.Blends of these low gas permeable polymers into polyester have not beensuccessful due to haze formed by the domains in the two-phase system.

The preferred polyamide is a partially aromatic polyamide containingmeta-xylylene groups, especially poly (m-xylylene adipamide), MXD6.

However, the use of partially aromatic polyamides as the low gaspermeable polymer gives an increase in the yellowness of the resultantcontainer.

U.S. Pat. No. 4,501,781 to Kushida et al. discloses a hollow blow-moldedbiaxially oriented bottle shaped container comprising a mixture ofpolyethylene terephthalate (PET) resin and a xylylene group-containingpolyamide resin. Both monolayer and multilayer containers are disclosed,but there is no information on the color of the bottles.

U.S. Pat. No. 5,650,469 to Long et al. discloses the use of aterephthalic acid based polyester blended with low levels (0.05 to 2.0wt-%) of a polyamide to reduce the acetaldehyde level of the container.These blends produced lower yellowness containers than a correspondingblend made from a dimethyl terephthalate based polyester, but are stillunsatisfactory for the higher levels required to significantly lower(decrease) the gas permeability.

U.S. Pat. Nos. 5,258,233, 5,266,413 and U.S. Pat. No. 5,340,884 to Millset al. discloses a polyester composition comprising 0.05 to 2.0 wt-% oflow molecular weight polyamide. At a 0.5 wt-% blend of MXD6 the haze ofthe bottle increased from 0.7 to 1.2%. No gas permeation or color datais given.

U.S. Pat. No. 4,837,115 to Igarashi et al. discloses a blend of aminoterminated polyamides with PET to reduce acetaldehyde levels. There wasno increase in haze with the addition of 0.5 wt-% MXD6, but at 2 wt-%the haze increased from 1.7 to 2.4%. No gas permeation or color data isgiven.

U.S. Pat. No. 6,239,233 to Bell et al. discloses a blend of acidterminated polyamides with PET that has reduced yellowness compared toamino terminated polyamides. No gas permeation data is given.

U.S. Pat. No. 6,346,307 to Al Ghatta et al. discloses the use of adianhydride of a tetracarboxylic acid to reduce the dispersed domainsize of a blend of MXD6 in PET. The examples did not give color data,but at a 10 wt-% MXD6 blend level the oxygen permeability was reducedfrom 0.53 to 0.12 ml/bottle/day/atm and the carbon dioxide permeabilitywas reduced from 18.2 to 7.02 ml/bottle/day/atm.

U.S. Pat. No. 6,444,283 to Turner et al. discloses that low molecularweight MXD6 polyamides have lower haze than higher molecular weight MXD6when blended with PET. The examples did not give color data, but at a 2wt-% MXD6 (Mitsubishi Chemical Company grade 6007) the oxygenpermeability of an oriented film was reduced from 8.1 to 5.7 cc-mil/100in.sup.2-atm-day compared to 6.1 for the low molecular weight MXD6.

U.S. Pat. No. 4,957,980 to Koyayashi et al. discloses the use of maleicanhydride grafted copolyesters to compatibilize polyester-MXD6 blends.Japanese Laid Open Patent Application No. 3-193325, 23 Aug. 1991, is afollow on to U.S. Pat. No. 4,957,980 and discloses that thedispersibility of a thermoplastic polyester component (A) and ameta-xylylene group containing polyamide component (B) and transparencyis improved by adding a compatibilizer component (C) and that the yellowcoloring as a result of adding component (C) is prevented by way ofadding a cobalt compound (component D) thus allowing a transparentmolded body for which coloring is prevented to be produced.

U.S. Pat. No. 4,499,262 to Fagerburg et al. discloses sulfo-modifiedpolyesters that give an improved rate of acetaldehyde generation and alower critical planar stretch ratio. Blends with polyamides were notdiscussed.

Japanese Pat. No. 2663578 B2 to Katsumasa et al. discloses the use of0.5 to 10 mole % 5-sulfoisophthalte copolymers as compatibilizer ofpolyester-MXD6 blends. No color data was given.

The use of a transition metal catalyst to promote oxygen scavenging inpolyamide multilayer containers, and blends with PET, has been disclosedin the following patents, for example.

U.S. Pat. Nos. 5,021,515, 5,639,815 and U.S. Pat. No. 5,955,527 toCochran et al. disclose the use of a cobalt salt as the preferredtransition metal catalyst and MXD6 as the preferred polyamide. There isno data on the color or haze of the polyamide blends.

U.S. Pat. Nos. 5,281,360 and 5,866,649 to Hong, and U.S. Pat. No.6,288,161 to Kim discloses blends of MXD6 with PET and a cobalt saltcatalyst. There is no data on the color or haze of the polyamide blends.

U.S. Pat. No. 5,623,047 to Yuo et al. discloses the use of a catalystcomposition containing an alkali metal acetate, preferably 30 ppm cobaltacetate to mask the yellowness in polyesters polymerized fromterephthalic acid.

U.S. Pat. Application 2003/0134966 A1 to Kim et al. discloses the use ofcobalt octoate and xylene group-containing polyamides for use inmulti-layer extrusion blow-molding for improved clarity. Extrusionblow-molding minimizes the orientation of the polyamide domain sizecompared to injection stretch blow molding containers. No color data isgiven.

U.S. Pat. No. 7,943,216 alleges that the ionic compatibilizer, incombination with a cobalt salt significantly reduces the yellowness ofthe resin, preform and container.

SUMMARY OF THE INVENTION

The present invention is an improvement over polyester/polyamide blendsknown in the art in that these compositions have a bright blue hue.

In the broadest sense the present invention comprises a polyester-cobaltcompound with a basic alkaline metal compound and optionally aphosphorous compound.

In the broadest sense the present invention comprises a compatibilizedblend of polyester-cobalt compound and a partially aromatic polyamidewith an ionic compatibilizer, a basic alkaline metal compound, e.g.alkaline metal base or basic alkaline metal salt, and optionallyphosphorous.

The broadest scope of the present invention also comprises a containerthat has both active and passive oxygen barrier and carbon dioxidebarrier properties at an improved color and clarity than containersknown in the art.

In the broadest sense the present invention also comprises a containerin which the balance of gas barrier properties and color can beindependently balanced.

In the broadest sense the present invention provides a method to blendpolyester and polyamides with an ionic compatibilizer and a cobalt salt.

In the broadest sense, the present invention provides for the use ofcobalt compounds and alkaline metal compounds to be melt blended withpolyester or polymerized with polyester or mixed via combination of meltblending and polymerizing to increase and control the blueness of thepolyester relative to the addition of the cobalt compound alone.

More specifically this invention is to the control using a compositioncomprising a polyester polymer comprising terephthalate moities reactedwith one or more glycols and at least 85% of the terephthalate moitiesare derived from a reaction of terephthalic acid or its dimethyl esterwith the at least one or more glycols, a plurality of alkaline metalions derived from at least one alkaline metal salt or base compound; anda plurality of cobalt ions having a positive metal charge, wherein atleast some of the cobalt ions are free cobalt ions; wherein the totalamount of cobalt ions are present at an amount selected from the groupconsisting of at least 0.2 mmoles, of at least 0.3 mmoles, of at least0.4 mmoles, of at least 0.7 mmoles, of at least 1.3 mmole, and of atleast 2.0 mmoles per kilogram of the composition, and the mole ratio ofthe alkaline metal ions to the free cobalt ions is in the range having alower ratio selected from 1:10, 3:10, 5:10, 6:10; 7:10 and an upperratio selected from the group consisting of 5:1, 4:1, 3:1, and 2:1.

It is further disclosed that the composition further comprise aplurality phosphorous ions wherein the molar ratio of the total amountof phosphorous ions to the total amount of cobalt ions is in the rangeselected from the group consisting of greater than 0:1 to 1.7:1, greaterthan 0:1 to 1.5:1, greater than 0:1 to 1.2:1, greater than 0:1 to 1.1:1,greater than 0:1 to 1.0:1, greater than 0:1 to 0.8:1 and greater than0:1 to 0.6:1.

The composition may further comprise an ionic compatibilizer derivedfrom sulfo-isophthalic acid or its dimethyl ester. The ioniccompatibilizer may be a metal sulfonate derived from thesulfo-isophthalic acid or its dimethyl ester and the metal of the metalsulfonate salt may not be lithium.

The composition may also be void of an ionic compatibilizer, or theionic compatibilizer may be void of lithium.

The ionic compatibilizer, if present, may be in a range from about 0.1to about 2.0 mole % of the polyester polymer. The amount of the cobaltions in the composition is in a range from about 20 to about 500 ppmbased upon the weight of the composition.

The composition may further comprises a partially aromatic polyamide.The partially aromatic polyamide can be selected from the groupconsisting of poly (metaxylene adipamide)(MXD6), poly(hexamethyleneisophthalamide), poly(hexamethylene adipamide-co-isophthalamide),poly(hexamethylene adipamide-co-terephthalamide), poly(hexamethyleneisophthalamide-co-terephthalamide), and mixtures of two or more ofthese.

The cobalt ions are derived from a cobalt salt selected from the groupconsisting of cobalt neodecanoate, cobalt acetate, cobalt chloride,cobalt oleate, cobalt linoleate, cobalt octoate, cobalt stearate, fattyacids and mixtures of two or more of these.

The plurality of alkaline metal ions can be selected from the groupconsisting of Na+, Ca++, and K+ or mixtures thereof. The plurality ofalkaline metal ions may not be exclusively lithium.

DETAILED DESCRIPTION OF THE INVENTION

Compositions of the present invention include an a polyester-cobaltcompound.

The composition may also be described as a polyester polymer comprisingterephthalate moities reacted with one or more glycols and at least 85%of the terephthalate moities are derived from a reaction of terephthalicacid or its dimethyl ester with the at least one or more glycols, with aplurality of alkaline metal ions derived from at least one alkalinemetal salt; and a plurality of cobalt ions having a positive metalcharge, wherein at least some of the cobalt ions are free cobalt ions;wherein the total amount of cobalt ions are present at an amountselected from the group consisting of at least 0.2 mmoles, of at least0.3 mmoles, of at least 0.4 mmoles, of at least 0.7 mmoles, of at least1.3 mmole, and of at least 2.0 mmoles per kilogram of the composition,and the mole ratio of the alkaline metal ions to the free cobalt ions isin the range having a lower ratio selected from 1:10, 3:10, 5:10, 6:10;7:10 and an upper ratio selected from the group consisting of 5:1, 4:1,3:1, and 2:1.

Generally polyesters can be prepared by one of two processes, namely:

(1) the ester process and

(2) the acid or ester process.

The ester process is where a dicarboxylic ester (such as dimethylterephthalate) is reacted with ethylene glycol or other diol in an esterinterchange reaction. Because the reaction is reversible, it isgenerally necessary to remove the alcohol (methanol when dimethylterephthalate is employed) to completely convert the raw materials intomonomers.

Certain catalysts are well known for use in the ester interchangereaction. In the past, catalytic activity was then sequestered byintroducing a phosphorus compound, for example polyphosphoric acid, atthe end of the ester interchange reaction. Primarily the esterinterchange catalyst was sequestered to prevent yellowness fromoccurring in the polymer.

According U.S. Pat. No. 7,943,216, and well known in the art, thecatalysts used for ester interchange are the acetates of zinc andmanganese.

Then the monomer undergoes polycondensation and the catalyst employed inthis reaction is generally an antimony, germanium or titanium compound,or a mixture of these. According U.S. Pat. No. 7,943,216, anitmonytri-oxide is an example of such a catalyst, called an additive.

According to U.S. Pat. No. 7,943,216, in the second method for makingpolyester, a di-acid (such as terephthalic acid) is reacted with a diol(such as ethylene glycol) by a direct esterification reaction producingmonomer and water. This reaction is also reversible like the esterprocess and thus to drive the reaction to completion one must remove thewater. According to U.S. Pat. No. 7,943,216 the direct esterificationstep does not require a catalyst. The monomer then undergoespolycondensation to form polyester just as in the ester process, and thecatalyst and conditions employed are generally the same as those for theester process.

For most container applications this melt phase polyester is furtherpolymerized to a higher molecular weight by a solid state or solid phasepolymerization (SSP).

In summary, in the ester process there are two steps, namely: (1) anester interchange, and (2) polycondensation. In the acid or esterprocess there are also two steps, namely: (1) direct esterification, and(2) polycondensation

According to U.S. Pat. No. 7,943,216 the direct esterification step doesnot require a catalyst. One of ordinary skill knows this very well anddoes not use a catalysts such as the acetate of zinc or manganese in themanufacture of an acid produced polyester. However, U.S. Pat. No.7,943,216 is not enabling to the acid or ester process for its claimedsynergy. In fact, in reviewing U.S. Pat. No. 7,943,216, it can be seenthat the only acid resin is resin A, but it is blended with S2 and aCobalt Masterbatch, therefore, there are no examples supporting a purelyacid based polyester.

It is therefore a purpose of this invention to provide polyester-cobaltcomposition and method to make such a composition. It is believed thatthe composition comprises a polyester-cobalt compound wherein the cobaltis coordinated with the carboxyl groups of the polyester.

Suitable polyesters are those produced from the reaction of a diacidcomprising at least 65 mol-% terephthalic acid, preferably at least 70mol-%, more preferably at least 75 mol-%, even more preferably, at least95 mol-%, and a diol component comprising at least 65% mol-% ethyleneglycol, preferably at least 70 mol-%, more preferably at least 75 mol-%,even more preferably at least 95 mol-%. It is also preferable that thediacid component is terephthalic acid and the diol component is ethyleneglycol, thereby forming polyethylene terephthalate (PET). The molepercent for all the diacid component totals 100 mol-%, and the molepercentage for all the diol component totals 100 mol-%.

The polyester-cobalt compound of this invention can also be described asa polyester wherein the polyester-cobalt compound comprises acidmoities, preferably terephthalate, reacted with one or more glycols andat least 85% of the acid moities are derived from a reaction of a diacidwith the at least one or more glycols. More preferably at least 90% ofthe di-acid moities, preferably terephthalate moities, are derived froma reaction of a diacid, preferably terephthalic acid, with the at leastone or more glycols. More preferably at least 95% of the acid moities,preferably terephthalate moities, derived from a reaction of a diacid,preferably terephthalic acid, with the at least one or more glycols.Most preferably 100% of the acid, preferably terephthalate, moities arederived from a reaction of a diacid, preferably terephthalic acid, withthe at least one or more glycols.

Where the polyester is modified by one or more diol components otherthan ethylene glycol, suitable diol components of the describedpolyester may be selected from 1,4-cyclohexandedimethanol,1,2-propanediol, 1,4-butanediol, 2,2-dimethyl-1,3-propanediol,2-methyl-1,3-propanediol (2MPDO) 1,6-hexanediol, 1,2-cyclohexanediol,1,4-cyclohexanediol, 1,2-cyclohexanedimethanol,1,3-cyclohexanedimethanol, and diols containing one or more oxygen atomsin the chain, e.g., diethylene glycol, triethylene glycol, dipropyleneglycol, tripropylene glycol or mixtures of these, and the like. Ingeneral, these diols contain 2 to 18, preferably 2 to 8 carbon atoms.Cycloaliphatic diols can be employed in their cis or trans configurationor as mixture of both forms. Preferred modifying diol components are1,4-cyclohexanedimethanol or diethylene glycol, or a mixture of these.

Where the polyester is modified by one or more acid components otherthan terephthalic acid, the suitable acid components (aliphatic,alicyclic, or aromatic dicarboxylic acids) of the linear polyester maybe selected, for example, from isophthalic acid,1,4-cyclohexanedicarboxylic acid, 1,3-cyclohexanedicarboxylic acid,succinic acid, glutaric acid, adipic acid, sebacic acid,1,12-dodecanedioic acid, 2,6-naphthalenedicarboxylic acid, bibenzoicacid, or mixtures of these and the like.

Also particularly contemplated by the present invention is a modifiedpolyester made by reacting at least 85 mol-% terephthalate from eitherterephthalic acid, and any of the above diacid comonomers with the atleast one diol.

In addition to polyester made from terephthalic acid and ethyleneglycol, or a modified polyester as stated above, the present inventionalso includes the use of 100% of an aromatic diacid such as2,6-naphthalene dicarboxylic acid or bibenzoic acid, and a modifiedpolyester made by reacting at least 85 mol-% of the dicarboxylate fromthese aromatic diacids with any of the above comonomers.

The present invention may also includes the use of up to 0.5 molepercent tri and higher functional acids or alcohols.

What has been discovered that against the teachings of U.S. Pat. No.7,943,216 and common knowledge to keep additives out of the acid orester process, certain additive when used in combination with a propercobalt compound will create a bright blue composition, at least brighterblue as measured by Hunter b* than the blue provided by the compositionwithout the alkaline base metal. It has also been found that thecomposition, believed to comprise a polyester-cobalt compound, will bemore blue regardless of the presence of an ionic compatibilizer, such assulfoisophthalic acid or a polyamide or other oxygen scavenger or blendcomponent. Thus the invention is operative in the absences of an ioniccompatabilizer or when the composition is void of an ioniccompatabilizer which is less than 0.1 mole percent.

In its simplest form, the polyester-cobalt composition can be made asfollows.

A base, preferable a basic alkaline metal compound, e.g. alkaline metalbase or basic alkaline metal salt, or alkaline metal base, such asLithium Acetate, sodium acetate, lithium hydroxide, and sodium hydroxidecan be introduced during, preferably at the beginning of, the polyesterpolymerization reaction of the acid or ester process. Duringpolymerization under vacuum the acetate is believed driven off in theform of acetic acid leaving the lithium ion, for example, to coordinatewith the carboxyl group of the polyester. When the polyester is blendedwith a cobalt salt, such as cobalt neodecanoate, the cobalt and lithiumions are believed to establish an equilibrium between the carboxyl ofthe polyester and the counterion of the cobalt salt. That is, at leastsome of the cobalt ions are removed from the neodecanoate and arereplaced by lithium ions, creating lithium neodecanoate, and the cobaltmoves and complexes with the carboxyl of the polyester, creating thepolyester-cobalt compound. The same is true for sodium ions.

The change in color is both visual and dramatic. Whereas, the polyesterwith just the cobalt salt does not have the bright blue color. That thecobalt is believed to be part of the polyester molecule can bedemonstrated by the back titration of the polyester-cobaltcompound/composition with a strong acid. When exposed to p-toluenesulfonic acid, the polyester-cobalt compound/composition returns to itsnatural color because the cobalt has been removed from the carboxylgroups of polyester and become part of the p-toluene sulfonic acid.

The alkaline metal ion may be any alkaline metal ion, including lithium,potassium and sodium, provided that the alkaline metal ion introducedfrom an ionic compatibilizer, if present, is not included as anoperative form of the alkaline metal. In other words, the alkaline metalion must be present in addition to any alkaline metals associated orderived from the ionic compatabilizer. The amount of alkaline metal ionsare present in the polyester-cobalt composition at a level selected fromthe group consisting of at least 0.2 mmoles, of at least 0.3 mmoles, ofat least 0.4 mmoles, of at least 0.7 mmoles, of at least 1.3 mmole, andof at least 2.0 mmoles per kilogram of polyester, wherein the alkalinemetal ions are not associated with or derived from an ioniccompatabilizer. As discussed above, the molar amount of the basicalkaline metal compound must be greater than the molar amount of anystrong acid optionally added to exhibit the improved color effect.

In addition to metal ions with +1 charge, Cesium, Et4N, Bu4N, Magnesium,Calcium might be useful. Any base compound will creates the bluingeffect. To use a base, the moles of alkali metal ions or replaced withthe moles of base add to the composition.

The phosphorous, which is optional, can be added as an activephosphorous compound, such as polyphosphoric acid, phosphoric acid, ortriethly phosphate, for example. An active phosphorous compound is acompound containing phosphorous, such as a phosphorous salt, and is acompound capable of reacting with the metal ions present in thepolyester-cobalt matrix. FeP (iron phosphide), is not an activephosphorous compound as it is well known that FeP is inert to the metalions in the polyester. In running the process, one is interested inkeeping the molar ratio of the amount of moles of phosphorous to molesof cobalt ions in a range selected from the group consisting of 0 to1.7, 0 to 1.5, 0 to 1.2, 0 to 1.1, 0 to 1.0, 0 to 0.8, and 0 to 0.6.Phosphorous when present would be in the range selected from the groupconsisting of greater than 0 to 1.7, greater than 0 to 1.5, greater than0 to 1.2, greater than 0 to 1.1, greater than 0 to 1.0, greater than 0to 0.8, and greater than 0 to 0.6.

It is noted that while the above example polymerizes the polyester inthe presence of the base, ideally the basic alkaline metal compound.Example 1 of the experimental section points out that the same effect isachieved by blending the cobalt and alkali metal base compounds intopolyester without polymerization.

The composition may also contain a polyamide. Preferably the polyamideused as the gas barrier component of the blend is selected from thegroup of partially aromatic polyamides is which the amide linkagecontains at least one aromatic ring and a non-aromatic conjugate.Preferred partially aromatic polyamides include: poly(m-xylyleneadipamide); poly(hexamethylene isophthalamide); poly(hexamethyleneadipamide-co-isophthalamide); poly(hexamethyleneadipamide-co-terephthalamide); poly(hexamethyleneisophthalamide-co-terephthalamide); or mixtures of two or more of these.The most preferred is poly(m-xylylene adipamide), alternatively known asMXD6 nylon.

The preferred range of polyamide is 1 to 10% by weight of thecomposition depending on the required gas barrier required for thecontainer. 2 to 8% by weight of the composition is also preferred, with3 to 8% by weight of the composition most preferred for the upper rangesand 1 to 5% by weight for the lower ranges.

The ionic compatibilizer is preferably a copolyester containing a metalsulfonate salt group attached to an aromatic nucleus. The metal ion ofthe sulfonate salt may be Na+, Li+, K+, Zn++, Mn++, Ca++ and the like.The metal ions from the sulfonate group may be multiple ions frommultiple different sulfonate groups.

The composition may be void of any metal ions derived from sulfonategroups. The composition may have metal ions from sulfonate groups whichare not exclusively lithium, i.e. a mixture of lithium and other ions.The composition may be void of a lithium ions derived from sulfonategroups.

Preferably, the aromatic acid nucleus is sulfophthalic acid,sulfoterephthalic acid, sulfoisophthalic acid,4-sulfonaphthalene-2,7-dicarboxylic acid, and their esters. Mostpreferably, the sulfomonomer is 5-sodiumsulfoisophthalic acid, 5-lithiumsulfoisophthalic acid or 5-zincsulfoisophthalic acid and most preferablytheir dialkyl esters such as the dimethyl ester (SIM) and glycol ester(SIPEG). The preferred range of 5-sodiumsulfoisophthalic, 5-lithiumsulfoisophthalic acid or 5-zincsulfoisophthalic acid to reduce the hazeof the container is 0.1 to 2.0 mol-% based upon the total moles of acidmoities in the polymer.

Suitable cobalt compounds for use with the present invention include,but are not limited to those cobalt compounds which have an acidconjugate. Such compounds include, but are not limited to those selectedfrom the group consisting of cobalt propionate, cobalt neodecanoate,cobalt acetate, cobalt carbonate, cobalt chloride, cobalt oleate, cobaltlinoleate, cobalt octoate, cobalt stearate, cobalt salt of a fatty acidwhich includes cobalt salts of short, medium and long chain fatty acids,or mixtures of two or more of these, among others.

As a transition metal catalyst for active oxygen scavenging, a cobaltsalt of a medium chain or long chain fatty acid is preferred. For colorcontrol of passive gas barrier blends any cobalt compound can be used,with cobalt acetate being preferred.

Color can be adjusted by varying the amount of moles of alkaline basemetal ion or base in the composition relative to the amount of molesfree cobalt ions in the composition. Free cobalt ions are those whichare not bound to phosphorous, such as described in RE-32765, theteachings of which are incorporated in their entirety. In other words,the moles of cobalt in excess of the moles of cobalt that will reactwith or are reacted the phosphorous ions. A shorthand way of doing thisis to use the total number of moles of cobalt, less the stoichiometricamount of phosphorous that is available to react with the cobalt toreact with the phosphate. Attention must be paid to the addition orderas

The preferred range of cobalt ions for blends containing the partiallyaromatic polyamide and 0.1 to 2.0 mol-% of an ionic compatibilizer basedupon the moles of acids or glycol moieties in the polyester is 20 to 500ppm of cobalt relative to the weight of the amount of polyester plusnylon. The alkaline metal ion not associated with or derived from theionic compatibilizer is preferably present in an amount of least 0.3mmoles per kilogram of polyester-cobalt compound, noting that all thecobalt which is not reacted with the phosphorous has been complexed withthe polyester, thus the moles of polyester cobalt compound equals themoles of cobalt not reacted with the phosphorous, also known as the freecobalt.

Although not required, additives may be used in the polyester/polyamideblend. Conventional known additives include, but are not limited to anadditive of a dye, pigment, filler, branching agent, reheat agent,anti-blocking agent, antioxidant, anti-static agent, biocide, blowingagent, coupling agent, flame retardant, heat stabilizer, impactmodifier, UV and visible light stabilizer, crystallization aid,lubricant, plasticizer, processing aid, acetaldehyde and otherscavengers, and slip agent, or a mixture thereof.

The polyester-cobalt composition (compound) can be conveniently preparedby polymerizing a polyester in the presence of the basic alkaline metalcompound, e.g. alkaline metal base or basic alkaline metal salt, havingan acid conjugate and then adding the cobalt as a cobalt salt to thefinished polymer via melt addition such as late addition to the reactor,during pelletizing, or later in an extrusion step such as at the throatof the injection molding machine that produces a preform that can bestretch blow molded into the shape of the container. The addition orderis not important, as the polyester could be polymerized it the presenceof the cobalt compound and the base, such as the alkaline metal base,added after polymerization.

The ionic compatibilizer can be copolymerized into the acid basedpolyester as indicated in US 20070088133.

If a conventional polyester base resin designed for polyester containersis used, then one method is to prepare a master batch of a polyestercontaining the ionic compatibilizer, and optionally a cobalt compound,together with the partially aromatic polyamide using a gravimetricfeeder for the three components. Alternatively the polyester resin canbe polymerized with an ionic compatibilizer, and optionally a transitionmetal catalyst for active scavenging, to form a copolymer. Thiscopolymer can be mixed at the injection molding machine with thepartially aromatic nylon. Alternative all the blend components can beblended together, or as a blend of master batches, and fed as a singlematerial to the extruder. The mixing section of the extruder should beof a design to produce a homogeneous blend.

It is also contemplated, that the addition of the basic alkaline metalto a polyester composition already containing cobalt, or the addition ofa basic alkali metal plus cobalt compound could occur via melt mixingduring the recycling or recovery process where the polyester resin isknown to yellow due to heat history and other ingredients. The use ofthe basic alkaline metal in conjunction with the cobalt provides aninexpensive way to control the color of the polyester composition. Thusthe use of a basic alkaline metal compound in conjunction with a cobaltsalt is contemplated. The basic alkaline metal compound or base is addedto recycled polyester/polyamide containing cobalt. The addition of thebasic compound can be used to control the color of the final meltblended composition when added according to the teachings of thisspecification.

In the contemplated process, when the recycled polyester resin, which ispolyester resin obtained from polyester preforms and/or polyesterbottles is pelletized it must pass through an extruder. During theextrusion process, the base, or alkali metal base, is added to thepolyester and melt mixed into the composition. If cobalt is not present,cobalt, in the form of a cobalt salt as described above can be added andmelt mixed as well. The ratio of base to cobalt can be controlled sothat the proper color is obtained.

The ingredients of the cobalt compound and basic alkaline metal compoundcan also be metal blended into the polyester polymer to make thecomposition. The composition may be free of ionic compatibilizers aswell.

EXPERIMENTAL

The following experiments establish that the presence or use of SodiumAcetate (NaAc, NaOAc, Na-Acetate) in combination with cobalt salts ineither PET or PET-SIPA dramatically shifts the b* of the resultingcomposition in the blue direction (−b*).

I. PET with Cobalt and Na.

-   -   The first set of experiments demonstrate the effect of cobalt        (Co-neodeconoate) and Na-Stearate combined with a commercial        grade PET-CLEARTUF 8006.    -   In this first set of experiments, PET, without SIPA, was melt        blended into preforms having an average b* of +5.74.    -   The PET, without SIPA, was then blended with Co-Neodecanoate at        a level of 100 ppm Cobalt in the final preform resulting in a        preform b* of +1.26. Thus, the visually blue Co-Neodecanoate at        100 ppm Co, shifted the b* in the blue direction −4.48 b* units        (5.74 to 1.26).    -   The PET was then blended with Co-Neodecanoate at 100 ppm cobalt        AND Na-Stearate at the level of 30 ppm sodium (Na) to yield a        preform having a b* of −3.72. Na-Stearate is colorless and is        known to yellow PET. But as the data shows, the color shift in        the presence of cobalt plus Na-Stearate is greater than the        shift due to the addition of Cobalt alone, indicating a        contribution from the Na-Stearate. The fact that 30 ppm Na        shifted the b* an additional −4.98 b* units to −3.72 indicates a        significant contribution from basic alkali metal Na, from sodium        stearate.    -   The next experiment melt blended 60 ppm Na, in the form of        Na-stearate with PET and cobalt neodecanoate at 100 ppm Cobalt        to produce a preform having a b* −8.24. The resultant effect of        the sodium at 60 ppm in combination with Cobalt at 100 pm is and        additional shift of −8.70 b* units compared to the addition of        Cobalt alone.

TABLE I Reduction due to Reduction due to b* Cobalt Na-Stearate PET+5.74 PET + Cobalt +1.26 −4.48 (1.26 − 5.74) (100 ppm) PET + Cobalt−3.72 −4.98 (−3.72 − 1.26) (100 ppm) + 30 ppm Na PET + Cobalt −8.24 −9.5 (−8.24 − 1.26) (100 ppm) + 60 ppm Na

These results indicate that at least 50% if not more of the b* shift cancome from the addition of the sodium.

II. SIPA-PET with Na-Acetate (without MXD6).

-   -   This next series of experiments demonstrates that the presence        of the basic alkali metala sodium, as Na-Acetate, at even very        low amounts has a dramatic effect on the b* values of the        SIPA-PET resins. The three resins used were, PET 8006C, and two        SIPA-PET resins each containing 1.3 mole % SIPA. The difference        was that one SIPA containing resin was polymerized with        approximately 165 ppm Na-Acetate trihydrate (27.9 ppm Na), the        other polymerized without Na-Acetate. Again, Co-Stearate, was        added to reach the level of 100 ppm cobalt in the final mixture.    -   In this set of experiments, the preforms made from the 8006C PET        resin had a b* of 2.75. This resin was blended with the 1.3 mole        % SIPA-PET without the Na-Acetate to achieve blends having 0.13,        0.26 and 0.5 mole percent SIPA respectively. As evident from        Table II, there is almost a linear increase of b* with the mole        % SIPA. NOTE: all ppm Na from Na-Acetate are nominal calculated        values.

TABLE II Without Na-Acetate 0 mole % 0.13 mole % 0.26 mole % 0.5 mole %Without Cobalt SIPA SIPA SIPA SIPA b* 2.75 4.45 6.24 9.28

-   -   Table III shows the blends of PET with the 1.3 mole % SIPA-PET        having 165 ppm Na-Acetate. Table IV compares the results of        Tables II and III.

TABLE III 0 mole % 0.13 mole % 0.26 mole % 0.5 mole % SIPA SIPA SIPASIPA With 0 ppm 2.9 ppm 5.6 ppm 10.6 ppm Na-Acetate Na from Na from Nafrom Nafrom Without Cobalt Na-Acetate Na-Acetate Na-Acetate Na-Acetateb* 3.07 3.48 4.29

TABLE IV 0 mole % 0.13 mole % 0.26 mole % 0.5 mole % SIPA SIPA SIPA SIPA0 ppm 2.9 ppm 5.6 ppm 10.6 ppm Na from Na from Na from Na from WithoutCobalt Na-Acetate Na-Acetate Na-Acetate Na-Acetate b*, no 2.75 4.45 6.249.28 Na-Acetate b*, with 3.07 3.48 4.29 Na-Acetate Effect of −1.38 −2.76−4.99 Na-Acetate

-   -   Again, there is an almost linear, negative relationship between        the Na-Acetate level and b* of the blends. As can be seen, the        addition of the Na-Acetate almost completely eliminates the        color contribution of the SIPA to the final blend.    -   In the next set of preforms, Cobalt, in the form of Co-Stearate        is added to achieve 100 ppm Cobalt level for all the preforms.        Table V shows the effect.

TABLE V Without 0 mole % Na-Acetate SIPA 0.13 mole % 0.26 mole % 0.5mole % 100 ppm Cobalt (PET) SIPA SIPA SIPA b*, no −4.20 −3.44 −0.79+1.94 Na-Acetate

-   -   As with the previous data without Cobalt, the preform color        almost linearly increases with increasing amounts of the        SIPA-PET without Na-Acetate.

TABLE VI 0 mole % 0.13 mole % 0.26 mole % 0.5 mole % With SIPA SIPA SIPASIPA Na-Acetate 0 ppm 2.9 ppm 5.6 ppm 10.6 ppm 100 ppm Na from Na fromNa from Na from Cobalt Na-Acetate Na-Acetate Na-Acetate Na-Acetate b*,with −6.77 −6.30 −4.87 Na-Acetate

TABLE VII Composite b* of 100 ppm Cobalt, with and without Na-Acetate 0mole % 0.13 mole % 0.26 mole % 0.5 mole % SIPA SIPA SIPA SIPA 0 ppm 2.9ppm 5.6 ppm 10.6 ppm 100 ppm Na from Na from Na from Na from CobaltNa-Acetate Na-Acetate Na-Acetate Na-Acetate b*, no −4.20 −3.44 −0.79+1.94 Na-Acetate b*, with NaAc −6.77 −6.30 −4.87 Effect of −3.33 −5.51−6.81 Na-Acetate

-   -   As can be seen from Table VII, the presence of the Na-Acetate,        in combination with cobalt shifts the b* to the blue (−b*). The        data can be recast to show the combined effects as in Table        VIII.

TABLE VIII 0 mole % 0.13 mole % 0.26 mole % 0.5 mole % SIPA SIPA SIPASIPA 0 ppm 2.9 ppm 5.6 ppm 10.6 ppm Na from Na from Na from Na fromNa-Acetate Na-Acetate Na-Acetate Na-Acetate WITHOUT COBALT b*, without2.75 4.45 6.24 9.28 Na-Acetate b*, with 3.07 3.48 4.29 Na-Acetate Effectof −1.38 −2.76 −4.99 Na-Acetate WITH 100 ppm COBALT b*, without −4.72−3.44 −0.79 +1.94 Na-Acetate b*, with NaAc −6.77 −6.30 −4.87 Effect of−3.33 −5.51 −6.81 Na-Acetate

-   -   The b* shift due to the Na-Acetate is much greater when in the        presence of Cobalt.        III. Impact of 5% MXD6.    -   The same set of experiments were repeated with 5% MXD6 added to        the blend.    -   In this set of experiments, the preforms made from the PET resin        had a b* of 3.52. This resin was blended with the 1.3 mole %        SIPA-PET without the Na-Acetate achieve blends having 0.13, 0.26        and 0.5 mole percent SIPA. The color of the preforms is shown in        the Table IX. As is evident, there is almost a linear increase        of b* with the mole % SIPA.

TABLE IX Without Na-Acetate Without Cobalt 0 mole % 0.13 mole % 0.26mole % 0.5 mole % 5% MXD6 SIPA SIPA SIPA SIPA b* 3.52 4.13 7.38 11.8

-   -   The next set of preforms were a blend of the PET with the 1.3        mole % SIPA having 165 ppm Sodium Acetate. Table X shows the        data

TABLE X 0 mole % 0.13 mole % 0.26 mole % 0.5 mole % With SIPA SIPA SIPASIPA Na-Acetate 0 ppm 2.9 ppm 5.6 ppm 10.6 ppm Without Cobalt Na from Nafrom Na from Na from 5% MXD6 Na-Acetate Na-Acetate Na-Acetate Na-Acetateb* 3.52 2.90 4.29 5.35

TABLE XI COMPARISON OF 0 mole % 0.13 mole % 0.26 mole % 0.5 mole % SIPASIPA SIPA SIPA 0 ppm 2.9 ppm 5.6 ppm 10.6 ppm Without Cobalt Na from Nafrom Na from Na from 5% MXD6 Na-Acetate Na-Acetate Na-Acetate Na-Acetateb*, no 3.52 4.13 7.38 11.80 Na-Acetate b*, with 2.90 4.29 5.35Na-Acetate Effect of −1.23 −3.09 −6.45 Na-Acetate

While the absolute values may have shifted with the presence of MXD6,the effect of the Na-Acetate in the blend on the b* color shows analmost linear relationship.

In the next set of preforms, Cobalt, in the form of Co-Stearate is addedto achieve 100 ppm Cobalt level for all the preforms.

TABLE XII Without Na-Acetate 0 mole % 100 ppm Cobalt SIPA 0.13 mole %0.26 mole % 0.5 mole % 5% MXD6 (PET) SIPA SIPA SIPA b* −4.34 −2.73 −0.64+4.12

-   -   As with the previous data without Cobalt, the preform color        almost linearly increases with increasing amounts of the        SIPA-PET without Na-Acetate.

TABLE XIII With 0 mole % 0.13 mole % 0.26 mole % 0.5 mole % Na-AcetateSIPA SIPA SIPA SIPA 100 ppm 0 ppm 2.9 ppm 5.6 ppm 10.6 ppm Cobalt Nafrom Na from Na from Na from 5% MXD6 Na-Acetate Na-Acetate Na-AcetateNa-Acetate b* −5.18 −3.58 −2.29

TABLE XIV 0 mole % 0.13 mole % 0.26 mole % 0.5 mole % SIPA SIPA SIPASIPA 0 ppm 2.9 ppm 5.6 ppm 10.6 ppm 100 ppm Na from Na from Na from Nafrom Cobalt Na-Acetate Na-Acetate Na-Acetate Na-Acetate b*, no −4.34−2.73 −0.64 +4.12 Na-Acetate b*, with −5.18 −3.58 −2.29 Na-AcetateEffect of −2.45 −2.94 −6.41 Na-Acetate

-   -   As can be seen, the presence of the Na-Acetate, in combination        with cobalt reduced the b*

The data can be recast to show the combined effects

TABLE XV 0 mole % 0.13 mole % 0.26 mole % 0.5 mole % SIPA SIPA SIPA SIPA0 ppm 2.9 ppm 5.6 ppm 10.6 ppm Na from Na from Na from Na from 5% MXD6Na-Acetate Na-Acetate Na-Acetate Na-Acetate WITHOUT COBALT b*, without3.52 4.13 7.38 11.8 Na-Acetate b*, with NaAc 2.90 4.29 5.35 Effect of−1.23 −3.09 −6.45 Na-Acetate WITH 100 ppm COBALT b*, without −4.34 −2.73−0.64 +4.12 Na-Acetate b*, with −5.18 −3.58 −2.29 Na-Acetate Effect of−2.45 −2.94 −6.41 Na-AcetateIV. Melt Polymerization Applicability

The general process is that an amount of terephthalic acid waspre-reacted with ethylene glycol to form a low molecular weight heel,called an E-T heel. The E-T heel was charged, as a ground solid to aglass tube reactor. Also charged was isophthalic acid and ethyleneglycol in an amount sufficient to react the isophthalic acid with theE-T heel. A typical charge was 100 grams of E-T heel and 1.02 grams ofisophthalic acid (IPA) with ethylene glycol (about 1.20 mole % of IPA onthe total acids). The material was heated to 150° C. and purged withnitrogen. After reaching 150° C., a solution of LiOAc, an alkaline basemetal, in ethylene glycol ([Li ion]=1% wt) was charged to the reactor.In one instance, the amount of lithium ions, added as an acetate, wasonly 0.005 parts per thousand (5 ppm) in the final product. Thiscorresponds to 0.05 grams of the 1% by weight lithium solution inethylene glycol. The amount of lithium acetate added is noted as ppmlithium and corresponds to 0.72 millimole alkaline metal compound (oralkaline metal)/kg of polymer.

After adding the lithium acetate, the mixture was heated to 260° C. andheld at that temperature for 30 minutes. The following was then added tothe reactor: a) 0.12 g of a solution of H₃PO₄ in ethylene glycol (1% byweight Phosphorous in ethylene glycol) and b) antimony as antimonyglycolate. The final concentration of phosphorous in the polyester was12 ppm and the concentration of antimony was 265 ppm. (In example 6, nophosphorous was added).

Vacuum was applied to the system to begin the polymerization step. Whenfull vacuum was reached the temperature was increased to 275° C. and thepolymerisation continued until the Intrinsic Viscosity of the polyesterwas about 0.6 dl/g.

Cobalt ions, in the amount of 110 ppm cobalt ions in the final product,were added by breaking the vacuum with nitrogen and adding the cobaltions in the form of cobalt neodecanoate pastilles and mixing forapproximately 5 minutes.

The polymer was extracted from the glass reactor and analyzed.

To produce the polyester with lithium sulfoisophthalic acidcopolymerized into the polymer, the sulfoisophthalic acid was firstpre-reacted with glycol to form the bis hydroxyethyl ester. Theconcentration of sulfoisophthalic bis hydroxyethyl ester was about 40%wt in ethylene glycol. Such solution of bis-ester was then diluted withethylene glycol and added to the reactor in one of two ways. One way wasto dilute the bis-ester with ethylene glycol to 20% wt and add it to theheel at 150° C. after the nitrogen purge. The other way was to dilutethe bis-ester with ethylene glycol to 5% wt and add it to the mixtureimmediately prior to the introduction of the vacuum (polymerizationcycle). In some instances, an additional amount of lithium acetate wasadded immediately prior to putting the reactor under vacuum.

There were many examples run to demonstrate this effect. Tables 1 liststhe most relevant examples establishing the invention.

To review, the heel for runs 2, 6, and 7/19, was heated and if present,esterified with the isophthalic acid in the presence of 0.005 pptlithium added as 1% by weight in ethylene glycol. For runs 2, 7/19 anadditional 0.045 ppt of Lithium, as 1% by weight in ethylene glycol wasadded immediately prior to polymerization.

From the data, it is apparent that the greater the alkaline metal ion,the more intense the blue, less yellow, demonstrating the role ofalkaline metal ion.

Although particular embodiments of the invention have been described indetail, it will be understood that the invention is not limitedcorrespondingly in scope, but include all changes and modificationscoming within the spirit and terms of the claims appended hereto.

TABLE XVI Sample ID 2 6 7 19 Formulation 2 6 7 7 TPA Heel gms 100 100100 100 IPA gms 1.02 0 1.54 1.54 (LiSIPA bi-ester 2.19 2.19 0 0 gms(Swenson 1B (39.9%)) for 0.5 mole % SIPA H₃PO₄ (1% in EG) 12 0 12 12 ppmP Li(OAc) (1% in EG) 50 5 50 50 ppm Li Sb (O₃ in EG) ppm 265 265 265 265Sb Co as Co 110 110 110 110 neodecanoate ppm Co IV 0.468 0.581 0.559COOH 28 41 22 L* 28.6 17.61 25.43 a* 1.35 −0.14 2.43 b* −9.8 −4.88 −15.3

We claim:
 1. A process for improving the color by lowering the b* of apolyester resin composition comprising a partially aromatic polyamideand a cobalt compound having free cobalt ions wherein the polyesterresin is obtained from polyester preforms or polyester bottles, saidprocess including the steps of: A. Extruding the polyester resincomposition comprising the partially aromatic polyamide and the cobaltcompound, wherein the amount of free cobalt ions present in thepolyester resin composition is in the range of 20 to 500 ppm based uponthe weight of the polyester resin composition; B. Melt mixing an amountof a base into the polyester resin comprising the partially aromaticpolyamide and the cobalt compound during the extruding step A, and C.Pelletizing the extruded polyester resin comprising the partiallyaromatic polyamide and the cobalt compound; wherein the base is analkali metal base having alkaline metal ions wherein the mole ratio ofalkaline metal ions to free cobalt ions is in the range of 1:10 to 3:1,and the alkaline metal ions are not associated with or derived from asulfonate group.
 2. The process according to claim 1, wherein the cobaltcompound is a cobalt salt.
 3. The process according to claim 1, whereinthe alkali metal base having alkaline metal ions is selected from thegroup consisting of lithium acetate, sodium acetate, lithium hydroxideand sodium hydroxide.
 4. A process for improving the color by loweringthe b* of a polyester resin composition comprising a partially aromaticpolyamide wherein the polyester resin comprising the partially aromaticpolyamide is obtained from polyester preforms or polyester bottles, saidprocess including the steps of: A. Extruding the polyester resincomprising the partially aromatic polyamide, B. Melt mixing an amount ofa base and an amount of a cobalt compound into the polyester resincomprising the partially aromatic polyamide during the extruding step A,wherein the amount of cobalt is sufficient to have free cobalt ionspresent in the polyester resin with the amount of free cobalt ions inthe range of 20 to 500 ppm based upon the weight of the polyester resincomposition and C. Pelletizing the extruded polyester resin comprisingthe partially aromatic polyamide; wherein the base is an alkali metalbase having alkaline metal ions wherein the mole ratio of alkaline metalions to free cobalt ions is in the range of 1:10 to 3:1, and thealkaline metal ions are not associated with or derived from a sulfonategroup.
 5. The process according to claim 4, wherein the cobalt compoundis a cobalt salt.
 6. The process according to claim 4, wherein thealkali metal base having alkaline metal ions is selected from the groupconsisting of lithium acetate, sodium acetate, lithium hydroxide andsodium hydroxide.